In a flashlight for use underwater, one of the major problems is making the switch watertight. Rubber diaphragms and covers have been used as outer seals and the switch must be operated through the seal. After prolonged use these seals wear and are prone to leakage. Other parts, such as removable ends for replacement of battery and bulb, also must be sealed and servicing the unit often results in damage to or destruction of the seals.